Infectious Diseases 1

Question 1

Which of the following is the most common cause for herpes labialis?

A) HSV-1
B) HSV-2
C) VZV
D) EBV
E) CMV

Answer 1

A) HSV-1 (cold sore)

Question 2

A 32 year old librarian presents to GP with a history of sharp tingling around his lips followed by a painful ulcer on the side of his mouth. O/E he has cervical lymphadenopathy and a blister on his finger. What is the pathogen?

A) Varicella Zoster Virus
B) Epstein-Barr Virus
C) Herpes Simplex Virus 1
D) Herpes Simplex Virus 2
E) Cytomegalovirus

Answer 2

C) Herpes Simplex Virus 1

- painful lateral mouth ulcer + lymphadenopathy + blister on finger (herpetic whitlow) = HSV-1

Question 3

A 6-year old girl presents with a fever of 38.5, fatigue and a itchy, maculopapular rash on her face and trunk. Other children at school present with similar symptoms. How should this patient be managed?

A) Hydration and NSAIDs.
B) Give oral acyclovir
C) Consider oral valaciclovir if within 24 h of rash onset
D) Paracetamol and Calamine lotion
E) Vaccinate with Varicella Immunoglobulin

Answer 3

D) Paracetamol and Calamine lotion

• chickenpox (varicella)
• Mx in children includes calamine lotion, analgesia, antihistamines
• Mx in adults includes above + antiviral if within 24hrs of rash onset

Question 4

A 50-year-old man presents with a rash as seen in this photo. Which of the following is NOT true?

A) This condition is Shingles
B) May occur due to stress
C) The rash may present bilaterally
D) Tingling in a dermatomal distribution
E) The rash is painful

Answer 4

C) The rash may present bilaterally
- shingles, reactivation of varicella to become zoster can be caused by stress, may have tingling in a dermatomal distribution, unilateral painful rash

Question 5

A wild medical student presents with sore throat and tonsillar exudates, posterior cervical lymphadenopathy and his basic observations are 38.9oC, HR is 90bpm and oxygen saturation on air is 99%. On examination there is splenomegaly. His condition is most likely due to which of the following?

A) EBV
B) Streptococcus pyogenes
C) Adenovirus
D) Covid-19
E) Candida

Answer 5

A) EBV
- tonsillar exudate + posterior cervical lymphadenopathy + fever + SPLENOMEGALY = infectious mononucleosis (caused by EBV)

Question 6

A 42-year-old man, previously treated for pneumocystic pneumonia and oral ulcers, presents with a purple, purpural lesion on his nose. Which is the causative organism for this skin lesion?

A) Staphylococcus Aureus
B) Malignant Melanoma
C) Human Immunodeficiency Virus
D) Human herpesvirus 6
E) Human Herpesvirus 8

Answer 6

E) Human Herpesvirus 8

• pneumocystic pneumonia indicates immunocompromise, oral ulcers + purple, purpural lesion = herpes
• HHV-8 most common in immunocompromised patients

Question 7

A 47-year-old HIV positive patient presents with weakness of his right leg, headaches, fever and confusion that have been getting worse for the last week. CT head shows multiple ring-enhancing lesions.

A) Plasmodium falciparum 
B) Neisseria meningitidis
C) Toxoplasma gondii
D) Herpes Simplex Encephalitis
E) Pox virus

Answer 7

C) Toxoplasma gondii
- signs of encephalitis and focal CNS deficits in immunocompromised patient + ring-enhancing lesions on head CT = toxoplasma

Question 8

A 13-year-old female patient presents to A&E with difficulty speaking. 4 days ago she experienced a sore, painful throat, which progressively got worse. She has difficulty swallowing.
On examination there is bilateral tonsillar exudate. There are 3 tender swellings on the anterior border of the sternocleidomastoid muscle and her observations are: T 39.1, HR 90, BP 113/68, SpO2 97% .
What is the most likely diagnosis?

A) Infectious mononucleosis
B) Viral tonsillitis
C) Common cold
D) Bacterial tonsillitis 
E) Chickenpox

Answer 8

D) Bacterial tonsillitis

• sore, painful throat, fever, tonsillar exudate (purulence), no cough mentioned = FeverPAIN score of 4 = Group A strep likely
• lymphadenopathy (anterior cervical here) also indicative of tonsillitis

Question 9

What is the most common causative agent for someone with a runny nose, sneezing and coughing (not during a pandemic)?

A) Rhinovirus 
B) Coronavirus 
C) Influenza 
D) Parainfluenza 
E) Respiratory syncytial virus

Answer 9

A) Rhinovirus

- most common cause of classic coryzal symptoms

Question 10

A 37-year-old presents with a lump on the posterior of his neck that is hot, erythematous and painful. What is the most likely causative agent?

A) Streptococcus pyogenes
B) Staphylococcus aureus
C) Mycobacterium Tuberculosis
D) Parasitic infection
E) Pseudomonas Aeruginosa

Answer 10

B) Staphylococcus aureus

- hot, erythematous, and painful lump on skin = abscess (s. aureus)